Frost Dates: First and last frost dates for deer flat dam, id
What's a safe temperature for tender plants? When the nightly temperature falls, frost can form, even above 32°, because the air is colder high above the ground and the frost can form up there and then fall down onto your garden and do some damage, even if it's 36° on the ground. So many factors come into play, including wind, concrete, houses, trees and other structures, etc etc etc. Because of all this, you might want to consider 36° as "the danger zone".
In your average springtime, you have a 90% chance that there will be no 36° nights by June 9. In other words, you can pretty much count on being safe from frost by that day. But we want to get those tomatoes in the ground as soon as possible, right? We see that there's still an 80% chance of 36° on April 29, so we don't dare plant that early. We wait a few days and by May 15 we are at the 50/50 point. At this point, we are close and we can start watching the weather forecast. If the upcoming week's forecast doesn't show below 40°, then it's probably okay to risk planting out your plants.
Temperature | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
---|---|---|---|---|---|---|---|---|---|
Last 16° | Mar 7 | Feb 25 | Feb 18 | Feb 12 | Feb 6 | Jan 31 | Jan 25 | Jan 17 | Jan 6 |
Last 20° | Mar 24 | Mar 15 | Mar 9 | Mar 4 | Feb 27 | Feb 22 | Feb 17 | Feb 11 | Feb 2 |
Last 24° | Apr 12 | Apr 3 | Mar 28 | Mar 23 | Mar 18 | Mar 14 | Mar 9 | Mar 3 | Feb 22 |
Last 28° | May 3 | Apr 26 | Apr 20 | Apr 15 | Apr 11 | Apr 7 | Apr 2 | Mar 28 | Mar 20 |
Last 32° | May 25 | May 16 | May 9 | May 3 | Apr 28 | Apr 22 | Apr 16 | Apr 9 | Mar 31 |
Last 36° | Jun 9 | Jun 1 | May 26 | May 20 | May 15 | May 11 | May 5 | Apr 29 | Apr 21 |
The charts on this page show the probabilities of receiving a certain temperature on a certain day. Some examples that might help:
- You have a small 20% chance of getting 32° by September 29.
- There is a 50% chance of being hit by a 32° frost starting around October 10
- You have a 80% chance of seeing 32° by October 21
- Said another way, you have a 1 in 5 chance at making it to that day without a 32° night.
Temperature | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
---|---|---|---|---|---|---|---|---|---|
First 16° | Nov 12 | Nov 20 | Nov 25 | Nov 30 | Dec 4 | Dec 8 | Dec 13 | Dec 20 | Jan 1 |
First 20° | Oct 26 | Nov 2 | Nov 7 | Nov 11 | Nov 16 | Nov 20 | Nov 24 | Nov 29 | Dec 6 |
First 24° | Oct 19 | Oct 25 | Oct 30 | Nov 3 | Nov 6 | Nov 10 | Nov 14 | Nov 18 | Nov 24 |
First 28° | Oct 6 | Oct 12 | Oct 16 | Oct 19 | Oct 22 | Oct 25 | Oct 29 | Nov 2 | Nov 7 |
First 32° | Sep 24 | Sep 29 | Oct 4 | Oct 7 | Oct 10 | Oct 14 | Oct 17 | Oct 21 | Oct 27 |
First 36° | Sep 14 | Sep 19 | Sep 23 | Sep 26 | Sep 29 | Oct 2 | Oct 5 | Oct 9 | Oct 14 |
Data is provided by the NOAA National Centers for Environmental Information.